This invention relates to a programmable logic device (PLD) in which cross-talk may be programmably cancelled. More particularly, this invention relates to the reuse of unused portions of a high-speed serial interface of a PLD to accomplish cross-talk cancellation.
It has become common for PLDs to incorporate high-speed serial interfaces to accommodate high-speed (i.e., greater than 1 Gbps) serial I/O standards—e.g., the XAUI (Extended Attachment Unit Interface) standard and other standards. Typically, PLDs having such interfaces have a large number of high-speed I/O channels, and cross-talk among those channels is a common difficulty to be overcome. For example, a common implementation for the aforementioned XAUI standard involves groups of four transceiver channels called “quads”, and there are usually several quads provided. There are thus many channels, and many opportunities for cross-talk.
It would be desirable to be able to provide a PLD in which cross-talk can be controlled without introducing a lot of extra circuitry.